Currently you can have Freesync or Crossfire in a game, until AMD puts new drivers out resolving the issue.
By default you activate the Freesync.
If the game you play supports crossfire and you have it configured as such, Freesync will be off. If it doesn't support crossfire, Freesync will be active.
Only the 295X2 requires to create custom profiles, to turn off crossfire on games that do not support it, so you can have the Freesync working.
As I said above, I mainly play MMOs, and all but one of them supports crossfire (TW Arena). The rest do not support CF, some they even crash if I do not turn off CF with custom profile (World of Tanks & World of Warships)
While other going to have some weird effects (Armored Warfare) if left on, there is a category which theoretically supports CF, but is better to play with Freesync on, since the engine is either bad (Elder Scrolls Online) or there is a hard cap on FPS (XCom), or pointless (Civilization, Beyond Earth)